IMM250 Midterm Exam Questions with 100% Correct Answers
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IMM250
IMM250 Midterm Exam Questions with 100% Correct Answers
What is the difference between prebiotics and probiotics? - Answer- Probiotics are live bacterial cultures that have beneficial effects on health (unproven)
Prebioticsare food for probiotics - non digestible carbs that provide energy source...
IMM250 Midterm Exam Questions
with 100% Correct Answers
What is the difference between prebiotics and probiotics? - Answer- Probiotics are live
bacterial cultures that have beneficial effects on health (unproven)
Prebioticsare food for probiotics - non digestible carbs that provide energy source for
bacteria
What are the harmful effects of gut bacteria? - Answer- Too much- ie appendix bursting
causes peritonitis which can be very severe.
In the wrong area - ie UTI
Microbiota and Obesity - Answer- Obesity is associated with:
- less microbial diversity in gut
reduced good"bacteroidetes" and over representation of other phyla
- microbes that are more efficient at lipid and carbohydrate metabolism (seen in mice)
What is the role of the epithelium in first line defence? - Answer- Produce mucin,
cytokines, chemotaxins, natural antibiotics (cationic antimicrobial peptides, defensins,
cathelicidins) transport antibiotics from lymph to GI
What do antimicrobial peptides do? - Answer- Antimicrobial peptides secreted by
epithelial cells are negatively charged and they bind with the positively charged bacterial
membranes and form a pore which kills the bacterial cell. Body cells are positively
charges so they are protected against this.
What is a pathogen? What are the two types? - Answer- An organism with virolence
factors encoded into their DNA and the ability to cross anatomical barriers to breach
defence of the organism being invaded. There are true or primary pathogens (cause
disease in those with a healthy immune system) and opportunistic pathogens (take
advantage of unhealthy immune systems)
What are the four ways that pathgens can become a problem to humans? - Answer- 1.
A foreign bacteria that enters the body as a pathogen (ie TB)
2. A bacteria that was part of the normal flora that gained virolence factors to make it
harmful to humans (ie e.coli)
3. A bacteria that is part of normal flora but causes disease when it gains access to
deep tissue.
4. In immunocompromized patients, normal microflora can cause infection
, What is Koch's Postulate? - Answer- How we can tell if a micobe is associated with
disease:
1. Microorganism is present in all cases of disease
2. Microorganism can be cultured from sick individual
3. Microorganism can infect someone else
4. Microorganism can be recovered and re-cultured from newly infected individual
This is how H. Pylori was found. Marshall innoculated himself.
Why are infectious diseases still a common cause of death? - Answer- 1. Growing link
between microbes and chronic disease
2. New emerging infections
3. Drug resistant microbes
Link between infection and chronic disease - Answer- cervical cancer and Human
papilloma
Liver cancer from Hepatitis A and B
Hodgkins from Epstein Barr
Atherosclerosis from chalymidia
Salmonella Typhimurum - Answer- A pathogen (in chicken) that breaks barriers
Has flagella, Adhesins to allow it to stick on to cells, and effector proteins from the
bacteria that hijack host cell proteins to allow bacterial entry and survival inside the cell.
It enters the glial cell of the stomach epithelium, enters cells and lives in a vacuole.
Causes inflammation, diarrhea and vomitting.
Shigella - Answer- bacillary dysentery - very few bacteria cause infection, usually
endemic. Portal of entry is M cells (secondary lymph tissue) to access the basal
membrane of epithelial cells because it cannot get through the apical membrane. Once
it is in the epithelia cells the vacuole breaks and it multiplies in the cytoplasm. Hijacks
the cells actin machinery to transport it around the cell and into neighbouring cells.
What is innate immunity? - Answer- Immunity system that we are born with, to protect
us from microbial infection. Present in all multicellular organisms.
What is the difference between innate and adaptive? - Answer- - Adaptive is newly
evolved and unique to vertebrates
- Innate has a set number of recognition molecules
- Innate cells react immediately, acquired needs priming
- Innate has no memory, opposite of acquired
Both are required for proper immune system function.
Absence of adaptive - infections cant be cleared, only controlled
Absence of innate - acquired cant be triggered, infections cant be cleared
Who discovered the innate system? - Answer- Metchnikoff first saw it in star fish -
phagocytes migrating to burns
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